The pyruvate dehydrogenase complex in cancer: An old metabolic gatekeeper regulated by new pathways and pharmacological agents

Regulation and tumor-suppressive function of the miR-379/miR-656 (C14MC) cluster in cervical cancer

Cervical cancer (CC) is a key contributor to cancer-related mortality in several countries. The identification of molecular markers and the underlying mechanism may help improve CC management. We studied the regulation and biological function of the chromosome 14 microRNA cluster (C14MC; miR-379/miR-656) in CC. Most C14MC members exhibited considerably lower expression in CC tissues and cell lines in The Cancer Genome Atlas (TCGA) cervical squamous cell carcinoma and endocervical adenocarcinoma patient cohorts. Bisulfite Sanger sequencing revealed hypermethylation of the C14MC promoter in CC tissues and cell lines. 5-aza-2 deoxy cytidine treatment reactivated expression of the C14MC members. We demonstrated that C14MC is a methylation-regulated miRNA cluster via artificial methylation and luciferase reporter assays. C14MC downregulation correlated with poor overall survival and may promote metastasis. C14MC activation via the lentiviral-based CRISPRa approach inhibited growth, proliferation, migration, and invasion; enhanced G2/M arrest; and induced senescence. Post-transcriptional regulatory network analysis of C14MC transcriptomic data revealed enrichment of key cancer-related pathways, such as metabolism, the cell cycle, and phosphatidylinositol 3-kinase (PI3K)-AKT signaling. Reduced cell proliferation, growth, migration, invasion, and senescence correlated with the downregulation of active AKT, MYC, and cyclin E1 (CCNE1) and the overexpression of p16, p21, and p27. We showed that C14MC miRNA activation increases reactive oxygen species (ROS) levels, intracellular Ca2+ levels, and lipid peroxidation rates, and inhibits epithelial-mesenchymal transition (EMT). C14MC targets pyruvate dehydrogenase kinase-3 (PDK3) according to the luciferase reporter assay. PDK3 is overexpressed in CC and is inversely correlated with C14MC. Both miR-494-mimic transfection and C14MC activation inhibited PDK3 expression. Reduced glucose uptake and lactate production, and upregulation of PDK3 upon C14MC activation suggest the potential role of these proteins in metabolic reprogramming. Finally, we showed that C14MC activation may inhibit EMT signaling. Thus, C14MC is a tumor-suppressive and methylation-regulated miRNA cluster in CC. Reactivation of C14MC can be useful in the management of CC.

12-O-deacetyl-phomoxanthone A inhibits ovarian tumor growth and metastasis by downregulating PDK4

AIMS

The xanthone dimer 12-O-deacetyl-phomoxanthone A (12-ODPXA) was extracted from the secondary metabolites of the endophytic fungus Diaporthe goulteri. The 12-ODPXA compound exhibited anticancer properties in murine lymphoma; however, the anti-ovarian cancer (OC) mechanism has not yet been explored. Therefore, the present study evaluated whether 12-ODPXA reduces OC cell proliferation, metastasis, and invasion by downregulating pyruvate dehydrogenase kinase (PDK)4 expression.

METHODS

Cell counting kit-8, colony formation, flow cytometry, wound healing, and transwell assays were performed to examine the effects of 12-ODPXA on OC cell proliferation, apoptosis, migration, and invasion. Transcriptome analysis was used to predict the changes in gene expression. Protein expression was determined using western blotting. Glucose, lactate, and adenosine triphosphate (ATP) test kits were used to measure glucose consumption and lactate and ATP production, respectively. Zebrafish xenograft models were constructed to elucidate the anti-OC effects of 12-ODPXA.

RESULTS

The 12-ODPXA compound inhibited OC cell proliferation, migration, invasion, and glycolysis while inducing cell apoptosis via downregulation of PDK4. In vivo experiments showed that 12-ODPXA suppressed tumor growth and migration in zebrafish.

CONCLUSION

Our data demonstrate that 12-ODPXA inhibits ovarian tumor growth and metastasis by downregulating PDK4, revealing the underlying mechanisms of action of 12-ODPXA in OC.

Metabolic adaptations in cancer stem cells: A key to therapy resistance

Cancer stem cells (CSCs) are a subset of tumor cells that can initiate and sustain tumor growth and cause recurrence and metastasis. CSCs are particularly resistant to conventional therapies compared to their counterparts, owing greatly to their intrinsic metabolic plasticity. Metabolic plasticity allows CSCs to switch between different energy production and usage pathways based on environmental and extrinsic factors, including conditions imposed by conventional cancer therapies. To cope with nutrient deprivation and therapeutic stress, CSCs can transpose between glycolysis and oxidative phosphorylation (OXPHOS) metabolism. The mechanism behind the metabolic pathway switch in CSCs is not fully understood, however, some evidence suggests that the tumor microenvironment (TME) may play an influential role mediated by its release of signals, such as Wnt/β-catenin and Notch pathways, as well as a background of hypoxia. Exploring the factors that promote metabolic plasticity in CSCs offers the possibility of eventually developing therapies that may more effectively eliminate the crucial tumor cell subtype and alter the disease course substantially.

Phosphorylation of FOXK2 at Thr13 and Ser30 by PDK2 sustains glycolysis through a positive feedback manner in ovarian cancer

Ovarian cancer is one of the most common gynecological malignant tumors with insidious onset, strong invasiveness, and poor prognosis. Metabolic alteration, particularly aerobic glycolysis, which is tightly regulated by transcription factors, is associated with the malignant behavior of OC. We screened FOXK2 in this study as a key transcription factor that regulates glycolysis in OC. FOXK2 is overly expressed in OC, and poor prognosis is predicted by overexpression. FOXK2 promotes OC cell proliferation both in vitro and in vivo and cell migration in vitro. Further studies showed that PDK2 directly binds to the forkhead-associated (FHA) domain of FOXK2 to phosphorylate FOXK2 at Thr13 and Ser30, thereby enhancing the transcriptional activity of FOXK2. FOXK2 transcriptionally regulates the expression of PDK2, thus forming positive feedback to sustain glycolysis in OC cells.

Inhalable metal-organic framework-mediated cuproptosis combined with PD-L1 checkpoint blockade for lung metastasis synergistic immunotherapy

Cuproptosis shows enormous application prospects in lung metastasis treatment. However, the glycolysis, Cu+ efflux mechanisms, and insufficient lung drug accumulation severely restrict cuproptosis efficacy. Herein, an inhalable poly (2-(N-oxide-N,N-diethylamino)ethyl methacrylate) (OPDEA)-coated copper-based metal-organic framework encapsulating pyruvate dehydrogenase kinase 1 siRNA (siPDK) is constructed for mediating cuproptosis and subsequently promoting lung metastasis immunotherapy, namely OMP. After inhalation, OMP shows highly efficient lung accumulation and long-term retention, ascribing to the OPDEA-mediated pulmonary mucosa penetration. Within tumor cells, OMP is degraded to release Cu2+ under acidic condition, which will be reduced to toxic Cu+ to induce cuproptosis under glutathione (GSH) regulation. Meanwhile, siPDK released from OMP inhibits intracellular glycolysis and adenosine-5'-triphosphate (ATP) production, then blocking the Cu+ efflux protein ATP7B, thereby rendering tumor cells more sensitive to OMP-mediated cuproptosis. Moreover, OMP-mediated cuproptosis triggers immunogenic cell death (ICD) to promote dendritic cells (DCs) maturation and CD8+ T cells infiltration. Notably, OMP-induced cuproptosis up-regulates membrane-associated programmed cell death-ligand 1 (PD-L1) expression and induces soluble PD-L1 secretion, and thus synergizes with anti-PD-L1 antibodies (aPD-L1) to reprogram immunosuppressive tumor microenvironment, finally yielding improved immunotherapy efficacy. Overall, OMP may serve as an efficient inhalable nanoplatform and afford preferable efficacy against lung metastasis through inducing cuproptosis and combining with aPD-L1.

Role of microRNA-363 during tumor progression and invasion

Recent progresses in diagnostic and therapeutic methods have significantly improved prognosis in cancer patients. However, cancer is still considered as one of the main causes of human deaths in the world. Late diagnosis in advanced tumor stages can reduce the effectiveness of treatment methods and increase mortality rate of cancer patients. Therefore, investigating the molecular mechanisms of tumor progression can help to introduce the early diagnostic markers in these patients. MicroRNA (miRNAs) has an important role in regulation of pathophysiological cellular processes. Due to their high stability in body fluids, they are always used as the non-invasive markers in cancer patients. Since, miR-363 deregulation has been reported in a wide range of cancers, we discussed the role of miR-363 during tumor progression and metastasis. It has been reported that miR-363 has mainly a tumor suppressor function through the regulation of transcription factors, apoptosis, cell cycle, and structural proteins. MiR-363 also affected the tumor progression via regulation of various signaling pathways such as WNT, MAPK, TGF-β, NOTCH, and PI3K/AKT. Therefore, miR-363 can be introduced as a probable therapeutic target as well as a non-invasive diagnostic marker in cancer patients.

Evaluation of IP3R3 Gene Silencing Effect on Pyruvate Dehydrogenase (PDH) Enzyme Activity in Breast Cancer Cells with and Without Estrogen Receptor

Background

Inositol 1,4,5-trisphosphate receptor (IP3R), a critical calcium ion (Ca2+) regulator, plays a vital role in breast cancer (BC) metabolism. Dysregulated IP3R in BC cells can drive abnormal growth or cell death. Estradiol increases IP3R type 3 (IP3R3) levels in BC, promoting cell proliferation and metabolic changes, including enhanced pyruvate dehydrogenase (PDH) activity, which, when reduced, leads to cell apoptosis. The study silenced IP3R3 to assess its impact on PDH.

Materials and Methods

The study used IP3R3 small interfering RNA (siRNA) to target Michigan Cancer Foundation-7 (MCF-7) and MDA-MB-231 cell lines. Transfection success was confirmed by flow cytometry. Cell viability and gene silencing were evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and real-time quantitative polymerase chain reaction (PCR) assays. Protein expression and cellular activity were analyzed through western blotting and PDH activity measurement.

Results

Transfecting MCF-7 and MDA-MB-231 cells with IP3R3 siRNA achieved a 65% transfection rate without significant toxicity. IP3R3 gene silencing effectively reduced IP3R3 messenger RNA (mRNA) and protein levels in both cell lines, leading to decreased PDH enzyme activity, especially in MDA-MB-231 cells.

Conclusion

The study highlights a link between high IP3R3 gene silencing and reduced PDH activity, with higher IP3R3 expression in estrogen-independent (MDA-MB-231) compared to estrogen-dependent (MCF-7) cell lines. This suggests a potential impact on BC metabolism and tumor growth via regulation of PDH activity.

Autocrine phosphatase PDP2 inhibits ferroptosis by dephosphorylating ACSL4 in the Luminal A Breast Cancer

Phosphatases can dephosphorylate phosphorylated kinases, leading to their inactivation, and ferroptosis is a type of cell death. Therefore, our aim is to identify phosphatases associated with ferroptosis by analyzing the differentially expressed genes (DEGs) of the Luminal A Breast Cancer (LumABC) cohort from the Cancer Genome Atlas (TCGA). An analysis of 260 phosphatase genes from the GeneCard database revealed that out of the 28 DEGs with high expression, only the expression of pyruvate dehydrogenase phosphatase 2 (PDP2) had a significant correlation with patient survival. In addition, an analysis of DEGs using gene ontology, Kyoto Encyclopedia of Genes and Genomes and gene set enrichment analysis revealed a significant variation in the expression of ferroptosis-related genes. To further investigate this, we analyzed 34 ferroptosis-related genes from the TCGA-LumABC cohort. The expression of long-chain acyl-CoA synthetase 4 (ACSL4) was found to have the highest correlation with the expression of PDP2, and its expression was also inversely proportional to the survival rate of patients. Western blot experiments using the MCF-7 cell line showed that the phosphorylation level of ACSL4 was significantly lower in cells transfected with the HA-PDP2 plasmid, and ferroptosis was correspondingly reduced (p < 0.001), as indicated by data from flow cytometry detection of membrane-permeability cell death stained with 7-aminoactinomycin, lipid peroxidation, and Fe2+. Immunoprecipitation experiments further revealed that the phosphorylation level of ACSL4 was only significantly reduced in cells where PDP2 and ACSL4 co-precipitated. These findings suggest that PDP2 may act as a phosphatase to dephosphorylate and inhibit the activity of ACSL4, which had been phosphorylated and activated in LumABC cells. Further experiments are needed to confirm the molecular mechanism of PDP2 inhibiting ferroptosis.

Vitamin-C-dependent downregulation of the citrate metabolism pathway potentiates pancreatic ductal adenocarcinoma growth arrest

In pancreatic ductal adenocarcinoma (PDAC), metabolic rewiring and resistance to standard therapy are closely associated. PDAC cells show enormous requirements for glucose-derived citrate, the first rate-limiting metabolite in the synthesis of new lipids. Both the expression and activity of citrate synthase (CS) are extraordinarily upregulated in PDAC. However, no previous relationship between gemcitabine response and citrate metabolism has been documented in pancreatic cancer. Here, we report for the first time that pharmacological doses of vitamin C are capable of exerting an inhibitory action on the activity of CS, reducing glucose-derived citrate levels. Moreover, ascorbate targets citrate metabolism towards the de novo lipogenesis pathway, impairing fatty acid synthase (FASN) and ATP citrate lyase (ACLY) expression. Lowered citrate availability was found to be directly associated with diminished proliferation and, remarkably, enhanced gemcitabine response. Moreover, the deregulated citrate-derived lipogenic pathway correlated with a remarkable decrease in extracellular pH through inhibition of lactate dehydrogenase (LDH) and overall reduced glycolytic metabolism. Modulation of citric acid metabolism in highly chemoresistant pancreatic adenocarcinoma, through molecules such as vitamin C, could be considered as a future clinical option to improve patient response to standard chemotherapy regimens.

Metformin Increases the Response of Cholangiocarcinoma Cells to Gemcitabine by Suppressing Pyruvate Kinase M2 to Activate Mitochondrial Apoptosis

BACKGROUND

Cholangiocarcinoma (CCA) is a malignant tumor with a high mortality rate. Resistance to chemotherapy remains a major challenge related to cancer treatment, and increasing the sensitivity of cancer cells to therapeutic drugs is a major focus of cancer treatment.

AIMS

We purposed to explore the role of Metformin in CCA involved in chemotherapeutic sensitivity and Pyruvate kinase M2 (PKM2) through regulating mitochondrial apoptosis in the present study.

METHODS

CCA cell lines of HCC9810 and RBE were treated with Metformin companied with antagonists or agonists of PKM2, cells sensitivity to Gemcitabine, cell migration and invasion along with apoptosis, which is mediated by JC-1 and LDH were assayed.

RESULTS

Our results indicated that Metformin and Gemcitabine exhibit synergistic effect on inhibition of cholangiocarcinoma cell viability, cell migration and invasion as well as promotion apoptosis of cholangiocarcinoma cells. In vivo, Metformin combined with Gemcitabine has cooperation in inhibiting the growth of cholangiocarcinoma cell-derived tumors. Moreover, Metformin and Gemcitabine inhibited expression of PKM2 and PDHB in HCC9810 and RBE.

CONCLUSION

Our study suggested that Metformin may increase the response of cholangiocarcinoma cells to Gemcitabine by suppressing PKM2 to activate mitochondrial apoptosis.

Disruption of mitochondrial pyruvate oxidation in dorsal root ganglia drives persistent nociceptive sensitization and causes pervasive transcriptomic alterations

ABSTRACT

Metabolism is inextricably linked to every aspect of cellular function. In addition to energy production and biosynthesis, metabolism plays a crucial role in regulating signal transduction and gene expression. Altered metabolic states have been shown to maintain aberrant signaling and transcription, contributing to diseases like cancer, cardiovascular disease, and neurodegeneration. Metabolic gene polymorphisms and defects are also associated with chronic pain conditions, as are increased levels of nerve growth factor (NGF). However, the mechanisms by which NGF may modulate sensory neuron metabolism remain unclear. This study demonstrated that intraplantar NGF injection reprograms sensory neuron metabolism. Nerve growth factor suppressed mitochondrial pyruvate oxidation and enhanced lactate extrusion, requiring 24 hours to increase lactate dehydrogenase A and pyruvate dehydrogenase kinase 1 (PDHK1) expression. Inhibiting these metabolic enzymes reversed NGF-mediated effects. Remarkably, directly disrupting mitochondrial pyruvate oxidation induced severe, persistent allodynia, implicating this metabolic dysfunction in chronic pain. Nanopore long-read sequencing of poly(A) mRNA uncovered extensive transcriptomic changes upon metabolic disruption, including altered gene expression, splicing, and poly(A) tail lengths. By linking metabolic disturbance of dorsal root ganglia to transcriptome reprogramming, this study enhances our understanding of the mechanisms underlying persistent nociceptive sensitization. These findings imply that impaired mitochondrial pyruvate oxidation may drive chronic pain, possibly by impacting transcriptomic regulation. Exploring these metabolite-driven mechanisms further might reveal novel therapeutic targets for intractable pain.

Analysis of the potential biological value of pyruvate dehydrogenase E1 subunit β in human cancer

BACKGROUND

The pyruvate dehydrogenase E1 subunit β (PDHB) gene which regulates energy metabolism is located in mitochondria. However, few studies have elucidated the role and mechanism of PDHB in different cancers.

AIM

To comprehensive pan-cancer analysis of PDHB was performed based on bioinformatics approaches to explore its tumor diagnostic and prognostic value and tumor immune relevance in cancer. In vitro experiments were performed to examine the biological regulation of PDHB in liver cancer.

METHODS

Pan-cancer data related to PDHB were obtained from the Cancer Genome Atlas (TCGA) database. Analysis of the gene expression profiles of PDHB was based on TCGA and Genotype Tissue Expression Dataset databases. Cox regression analysis and Kaplan-Meier methods were used to assess the correlation between PDHB expression and survival prognosis in cancer patients. The correlation between PDHB and receiver operating characteristic diagnostic curve, clinicopathological staging, somatic mutation, tumor mutation burden (TMB), microsatellite instability (MSI), DNA methylation, and drug susceptibility in pan-cancer was also analyzed. Various algorithms were used to analyze the correlation between PDHB and immune cell infiltration and tumor chemotaxis environment, as well as the co-expression analysis of PDHB and immune checkpoint (ICP) genes. The expression and functional phenotype of PDHB in single tumor cells were studied by single-cell sequencing, and the functional enrichment analysis of PDHB-related genes was performed. The study also validated the level of mRNA or protein expression of PDHB in several cancers. Finally, in vitro experiments verified the regulatory effect of PDHB on the proliferation, migration, and invasion of liver cancer.

RESULTS

PDHB was significantly and differently expressed in most cancers. PDHB was significantly associated with prognosis in patients with a wide range of cancers, including kidney renal clear cell carcinoma, kidney renal papillary cell carcinoma, breast invasive carcinoma, and brain lower grade glioma. In some cancers, PDHB expression was clearly associated with gene mutations, clinicopathological stages, and expression of TMB, MSI, and ICP genes. The expression of PDHB was closely related to the infiltration of multiple immune cells in the immune microenvironment and the regulation of tumor chemotaxis environment. In addition, single-cell sequencing results showed that PDHB correlated with different biological phenotypes of multiple cancer single cells. This study further demonstrated that down-regulation of PDHB expression inhibited the proliferation, migration, and invasion functions of hepatoma cells.

CONCLUSION

As a member of pan-cancer, PDHB may be a novel cancer marker with potential value in diagnosing cancer, predicting prognosis, and in targeted therapy.

Association of 2-oxoacid dehydrogenase complexes with respirasomes in mitochondria

In the present study, cryo-electron tomography was used to investigate the localization of 2-oxoacid dehydrogenase complexes (OADCs) in cardiac mitochondria and mitochondrial inner membrane samples. Two classes of ordered OADC inner cores with different symmetries were distinguished and their quaternary structures modeled. One class corresponds to pyruvate dehydrogenase complexes and the other to dehydrogenase complexes of α-ketoglutarate and branched-chain α-ketoacids. OADCs were shown to be localized in close proximity to membrane-embedded respirasomes, as observed both in densely packed lamellar cristae of cardiac mitochondria and in ruptured mitochondrial samples where the dense packing is absent. This suggests the specificity of the OADC-respirasome interaction, which allows localized NADH/NAD+ exchange between OADCs and complex I of the respiratory chain. The importance of this local coupling is based on OADCs being the link between respiration, glycolysis and amino acid metabolism. The coupling of these basic metabolic processes can vary in different tissues and conditions and may be involved in the development of various pathologies. The present study shows that this important and previously missing parameter of mitochondrial complex coupling can be successfully assessed using cryo-electron tomography.

Metabolomics and mitochondrial dysfunction in cardiometabolic disease

Circulating metabolites are indicators of systemic metabolic dysfunction and can be detected through contemporary techniques in metabolomics. These metabolites are involved in numerous mitochondrial metabolic processes including glycolysis, fatty acid β-oxidation, and amino acid catabolism, and changes in the abundance of these metabolites is implicated in the pathogenesis of cardiometabolic diseases (CMDs). Epigenetic regulation and direct metabolite-protein interactions modulate metabolism, both within cells and in the circulation. Dysfunction of multiple mitochondrial components stemming from mitochondrial DNA mutations are implicated in disease pathogenesis. This review will summarize the current state of knowledge regarding: i) the interactions between metabolites found within the mitochondrial environment during CMDs, ii) various metabolites' effects on cellular and systemic function, iii) how harnessing the power of metabolomic analyses represents the next frontier of precision medicine, and iv) how these concepts integrate to expand the clinical potential for translational cardiometabolic medicine.

New Steroidal Selenides as Proapoptotic Factors

Cytostatic and pro-apoptotic effects of selenium steroid derivatives against HeLa cells were determined. The highest cytostatic activity was shown by derivative 4 (GI50 25.0 µM, almost complete growth inhibition after three days of culture, and over 97% of apoptotic and dead cells at 200 µM). The results of our study (cell number measurements, apoptosis profile, relative expression of apoptosis-related APAF1, BID, and mevalonate pathway-involved HMGCR, SQLE, CYP51A1, and PDHB genes, and computational chemistry data) support the hypothesis that tested selenosteroids induce the extrinsic pathway of apoptosis by affecting the cell membrane as cholesterol antimetabolites. An additional mechanism of action is possible through a direct action of derivative 4 to inhibit PDHB expression in a way similar to steroid hormones.

Relationship between transcriptional expression of pyruvate dehydrogenase and local control of disease in patients with oral cavity carcinomas

BACKGROUND

The altered cellular metabolism is one of the hallmarks of the cancer cells, favoring the process of aerobic glycolysis, known as the Warburg effect. The pyruvate dehydrogenase (PDH) complex is one of the elements involved in this metabolic process. The present study aims to evaluate the relationship between the transcriptional expression of PDHB and the risk of local recurrence in patients with oral cavity carcinomas.

METHODS

We determined the transcriptional expression of PDHB in biopsies from 41 patients with oral cavity carcinomas treated with surgery. The PDHB expression was categorized according to the local control of the disease with a recursive partitioning analysis.

RESULTS

During the follow-up period 13 patients (31.7%) had a local recurrence of the tumor. Considering local disease control as the dependent variable, the recursive partitioning analysis classified the patients in two categories according to high (n=16, 39.0%) or low (n=25, 61.0%) PDHB expression. Five-year local recurrence-free survival for patients with high PDHB expression was 84.8% (95% CI: 65.2-100%), and for patients with low expression it was 54.3% (95% CI: 34.3-74.2 %) (P=0.034). The results of multivariate analysis showed that patients with a low PDHB expression had a 4.90 times higher risk of local recurrence of the tumor (95% CI: 1.02-22.68, P=0.042).

CONCLUSION

There is a relationship between the metabolic characteristics of the tumor and its aggressiveness. According to our results, patients with oral cavity carcinomas with low transcriptional expression levels of PDHB have a significantly higher risk of local tumor recurrence.

Determination of key events in mouse hepatocyte maturation at the single-cell level

Hepatocytes, the liver's predominant cells, perform numerous essential biological functions. However, crucial events and regulators during hepatocyte maturation require in-depth investigation. In this study, we performed single-cell RNA sequencing (scRNA-seq) and single-nucleus RNA sequencing (snRNA-seq) to explore the precise hepatocyte development process in mice. We defined three maturation stages of postnatal hepatocytes, each of which establishes specific metabolic functions and exhibits distinct proliferation rates. Hepatic zonation is gradually formed during hepatocyte maturation. Hepatocytes or their nuclei with distinct ploidies exhibit zonation preferences in distribution and asynchrony in maturation. Moreover, by combining gene regulatory network analysis with in vivo genetic manipulation, we identified critical maturation- and zonation-related transcription factors. This study not only delineates the comprehensive transcriptomic profiles of hepatocyte maturation but also presents a paradigm to identify genes that function in the development of hepatocyte maturation and zonation by combining genetic manipulation and measurement of coordinates in a single-cell developmental trajectory.

Identification of cuproptosis-related subtypes, characterization of immune microenvironment infiltration, and development of a prognosis model for osteoarthritis

Background

Osteoarthritis (OA) is a prevalent chronic joint disease with an obscure underlying molecular signature. Cuproptosis plays a crucial role in various biological processes. However, the association between cuproptosis-mediated immune infifiltration and OA progression remains unexplored. Therefore, this study elucidates the pathological process and potential mechanisms underlying cuproptosis in OA by constructing a columnar line graph model and performing consensus clustering analysis.

Methods

Gene expression profifile datasets GSE12021, GSE32317, GSE55235, and GSE55457 of OA were obtained from the comprehensive gene expression database. Cuproptosis signature genes were screened by random forest (RF) and support vector machine (SVM). A nomogram was developed based on cuproptosis signature genes. A consensus clustering was used to distinguish OA patients into different cuproptosis patterns. To quantify the cuproptosis pattern, a principal component analysis was developed to generate the cuproptosis score for each sample. Single-sample gene set enrichment analysis (ssGSEA) was used to provide the abundance of immune cells in each sample and the relationship between these significant cuproptosis signature genes and immune cells.To quantify the cuproptosis pattern, a principal component analysis technique was developed to generate the cuproptosis score for each sample. Cuproptosis-related genes were extracted and subjected to differential expression analysis to construct a disease prediction model and confifirmed by RT-qPCR.

Results

Seven cuproptosis signature genes were screened (DBT, LIPT1, GLS, PDHB, FDX1, DLAT, and PDHA1) to predict the risk of OA disease. A column line graph model was developed based on these seven cuproptosis signature genes, which may assist patients based on decision curve analysis. A consensus clustering method was used to distinguish patients with disorder into two cuproptosis patterns (clusters A and B). To quantify the cuproptosis pattern, a principal component analysis technique was developed to generate the cuproptosis score for each sample. Furthermore, the OA characteristics of patients in cluster A were associated with the inflflammatory factors IL-1b, IL-17, IL-21, and IL-22, suggesting that the cuproptosis signature genes play a vital role in the development of OA.

Discussion

In this study, a risk prediction model based on cuproptosis signature genes was established for the fifirst time, and accurately predicted OA risk. In addition, patients with OA were classifified into two cuproptosis molecule subtypes (clusters A and B); cluster A was highly associated with Th17 immune responses, with higher IL-1b, IL-17, and IL-21 IL-22 expression levels, while cluster B had a higher correlation with cuproptosis. Our analysis will help facilitate future research related cuproptosis-associated OA immunotherapy. However, the specifific mechanisms remain to be elucidated.

Phytochemicals targeting glycolysis in colorectal cancer therapy: effects and mechanisms of action

Colorectal cancer (CRC) is the third most common malignant tumor in the world, and it is prone to recurrence and metastasis during treatment. Aerobic glycolysis is one of the main characteristics of tumor cell metabolism in CRC. Tumor cells rely on glycolysis to rapidly consume glucose and to obtain more lactate and intermediate macromolecular products so as to maintain growth and proliferation. The regulation of the CRC glycolysis pathway is closely associated with several signal transduction pathways and transcription factors including phosphatidylinositol 3-kinases/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR), adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK), hypoxia-inducible factor-1 (HIF-1), myc, and p53. Targeting the glycolytic pathway has become one of the key research aspects in CRC therapy. Many phytochemicals were shown to exert anti-CRC activity by targeting the glycolytic pathway. Here, we review the effects and mechanisms of phytochemicals on CRC glycolytic pathways, providing a new method of drug development.

Comprehensive analysis identifies cuproptosis-related gene DLAT as a potential prognostic and immunological biomarker in pancreatic adenocarcinoma

BACKGROUND

Cuproptosis is a regulated cell death form associated with tumor progression, clinical outcomes, and immune response. However, the role of cuproptosis in pancreatic adenocarcinoma (PAAD) remains unclear. This study aims to investigate the implications of cuproptosis-related genes (CRGs) in PAAD by integrated bioinformatic methods and clinical validation.

METHODS

Gene expression data and clinical information were downloaded from UCSC Xena platform. We analyzed the expression, mutation, methylation, and correlations of CRGs in PAAD. Then, based on the expression profiles of CRGs, patients were divided into 3 groups by consensus clustering algorithm. Dihydrolipoamide acetyltransferase (DLAT) was chosen for further exploration, including prognostic analysis, co-expression analysis, functional enrichment analysis, and immune landscape analysis. The DLAT-based risk model was established by Cox and LASSO regression analysis in the training cohort, and then verified in the validation cohort. Quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) and immunohistochemistry (IHC) assays were performed to examine the expression levels of DLAT in vitro and in vivo, respectively.

RESULTS

Most CRGs were highly expressed in PAAD. Among these genes, increased DLAT could serve as an independent risk factor for survival. Co-expression network and functional enrichment analysis indicated that DLAT was engaged in multiple tumor-related pathways. Moreover, DLAT expression was positively correlated with diverse immunological characteristics, such as immune cell infiltration, cancer-immunity cycle, immunotherapy-predicted pathways, and inhibitory immune checkpoints. Submap analysis demonstrated that DLAT-high patients were more responsive to immunotherapeutic agents. Notably, the DLAT-based risk score model possessed high accuracy in predicting prognosis. Finally, the upregulated expression of DLAT was verified by RT-qPCR and IHC assays.

CONCLUSIONS

We developed a DLAT-based model to predict patients' clinical outcomes and demonstrated that DLAT was a promising prognostic and immunological biomarker in PAAD, thereby providing a new possibility for tumor therapy.

Integrated single-cell and bulk characterization of cuproptosis key regulator PDHB and association with tumor microenvironment infiltration in clear cell renal cell carcinoma

Background

Renal clear cell carcinoma (ccRCC) is one of the most prevalent cancers worldwide. Accumulating evidence revealed that copper-induced cell death played a vital role in various tumors. However, the underlying mechanism of cuproptosis with molecular heterogeneity and tumor microenvironment (TME) in ccRCC remains to be elucidated. The present study aimed to discover the biological function of cuproptosis regulators with the potential to guide clinical therapy.

Methods

Using Single-cell RNA-seq, bulk transcriptome and other multi-omics datasets, we identify essential cuproptosis-related hub gene PDHB for further study. The dysregulation of PDHB in ccRCC was characterized, together with survival outcomes, pathway enrichment and immune infiltration among tumor microenvironments. The functional significance and clinical association of PDHB was validated with loss of function experiments and surgical removal specimens.

Results

PDHB mRNA and protein expression level was significantly downregulated in ccRCC tissues compared with normal and paired normal tissues. Clinicopathological parameters and tissue microarray (TMA) indicated that PDHB was identified as a prognostic factor for survival outcomes among ccRCC patients. Additionally, low PDHB was negatively correlated with Treg cells, indicating an immunosuppressive microenvironment. Mechanistically, knockdown PDHB appeared to promote the RCC cells proliferation, migration, and invasion potentials. Subsequent studies showed that copper-induced cell death activation could overcome sunitinib resistance in RCC cells.

Conclusion

This research illustrated a cuproptosis-related hub gene PDHB which could serve as a potential prognostic marker and provide therapeutic benefits for clinical treatment of ccRCC patients.

Orchestration of Mitochondrial Function and Remodeling by Post-Translational Modifications Provide Insight into Mechanisms of Viral Infection

The regulation of mitochondria structure and function is at the core of numerous viral infections. Acting in support of the host or of virus replication, mitochondria regulation facilitates control of energy metabolism, apoptosis, and immune signaling. Accumulating studies have pointed to post-translational modification (PTM) of mitochondrial proteins as a critical component of such regulatory mechanisms. Mitochondrial PTMs have been implicated in the pathology of several diseases and emerging evidence is starting to highlight essential roles in the context of viral infections. Here, we provide an overview of the growing arsenal of PTMs decorating mitochondrial proteins and their possible contribution to the infection-induced modulation of bioenergetics, apoptosis, and immune responses. We further consider links between PTM changes and mitochondrial structure remodeling, as well as the enzymatic and non-enzymatic mechanisms underlying mitochondrial PTM regulation. Finally, we highlight some of the methods, including mass spectrometry-based analyses, available for the identification, prioritization, and mechanistic interrogation of PTMs.

The expression pattern of pyruvate dehydrogenase kinases predicts prognosis and correlates with immune exhaustion in clear cell renal cell carcinoma

Renal cancer cells constitute a paradigm of tumor cells with a glycolytic reprogramming which drives metabolic alterations favouring cell survival and transformation. We studied the expression and activity of pyruvate dehydrogenase kinases (PDK1-4), key enzymes of the energy metabolism, in renal cancer cells. We analysed the expression, subcellular distribution and clinicopathological correlations of PDK1-4 by immunohistochemistry of tumor tissue microarray samples from a cohort of 96 clear cell renal cell carcinoma (ccRCC) patients. Gene expression analysis was performed on whole tumor tissue sections of a subset of ccRCC samples. PDK2 and PDK3 protein expression in tumor cells correlated with lower patient overall survival, whereas PDK1 protein expression correlated with higher patient survival. Gene expression analysis revealed molecular association of PDK2 and PDK3 expression with PI3K signalling pathway, as well as with T cell infiltration and exhausted CD8 T cells. Inhibition of PDK by dichloroacetate in human renal cancer cell lines resulted in lower cell viability, which was accompanied by an increase in pAKT. Together, our findings suggest a differential role for PDK enzymes in ccRCC progression, and highlight PDK as actionable metabolic proteins in relation with PI3K signalling and exhausted CD8 T cells in ccRCC.

The mechanism of whey protein and blueberry juice mixed system fermented with Lactobacillus inhibiting Escherichia coli during storage

The aim of this study was to identify the antimicrobial effect and mechanism of whey protein and blueberry juice mixed systems fermented with Lactobacillus against Escherichia coli during storage. The whey protein and blueberry juice mixed systems were fermented with L. casei M54, L. plantarum 67, S. thermophiles 99 and L. bulgaricus 134 and had different antibacterial activities against E. coli during storage. The antimicrobial activity of the mixed whey protein and blueberry juice mixture systems was the highest, with an inhibition zone diameter of approximately 230 mm, compared with the whey protein or blueberry juice systems alone. There were no viable E. coli cells 7 h after treatment with of the whey protein and blueberry juice mixed systems as determined by survival curve analysis. Analysis of the inhibitory mechanism showed that the release of alkaline phosphatase, electrical conductivity, protein and pyruvic acid contents, and aspartic acid transaminase and alanine aminotransferase activity in E. coli increased. These results demonstrated that these mixed systems fermented with Lactobacillus, especially those containing blueberries, could inhibit the growth of E. coli and even cause cell death by destroying the cell membrane and cell wall.

Regulation of tumor metabolism by post translational modifications on metabolic enzymes

Metabolic reprogramming is a hallmark of cancer development, progression, and metastasis. Several metabolic pathways such as glycolysis, tricarboxylic acid (TCA) cycle, lipid metabolism, and glutamine catabolism are frequently altered to support cancer growth. Importantly, the activity of the rate-limiting metabolic enzymes in these pathways are specifically modulated in cancer cells. This is achieved by transcriptional, translational, and post translational regulations that enhance the expression, activity, stability, and substrate sensitivity of the rate-limiting enzymes. These mechanisms allow the enzymes to retain increased activity supporting the metabolic needs of rapidly growing tumors, sustain their survival in the hostile tumor microenvironments and in the metastatic lesions. In this review, we primarily focused on the post translational modifications of the rate-limiting enzymes in the glucose and glutamine metabolism, TCA cycle, and fatty acid metabolism promoting tumor progression and metastasis.

The Role of Regulated Programmed Cell Death in Osteoarthritis: From Pathogenesis to Therapy

Osteoarthritis (OA) is a worldwide chronic disease that can cause severe inflammation to damage the surrounding tissue and cartilage. There are many different factors that can lead to osteoarthritis, but abnormally progressed programmed cell death is one of the most important risk factors that can induce osteoarthritis. Prior studies have demonstrated that programmed cell death, including apoptosis, pyroptosis, necroptosis, ferroptosis, autophagy, and cuproptosis, has a great connection with osteoarthritis. In this paper, we review the role of different types of programmed cell death in the generation and development of OA and how the different signal pathways modulate the different cell death to regulate the development of OA. Additionally, this review provides new insights into the radical treatment of osteoarthritis rather than conservative treatment, such as anti-inflammation drugs or surgical operation.

Cuproptosis-Related Gene DLAT as a Novel Biomarker Correlated with Prognosis, Chemoresistance, and Immune Infiltration in Pancreatic Adenocarcinoma: A Preliminary Study Based on Bioinformatics Analysis

A novel form of cell death, cuproptosis, was recently identified to be mediated by the binding of copper to lipoylated enzymes of the tricarboxylic acid cycle. Cuproptosis-related genes (CRGs) may play a crucial role in the progression of pancreatic adenocarcinoma (PAAD), which often exhibits metabolic reprogramming. In the present study, univariate Cox regression analysis and Kaplan–Meier survival analysis were performed to identify prognostic CRGs. Data from the Cancer Therapeutics Response Portal and the Genomics of Drug Sensitivity in Cancer database were downloaded for drug sensitivity analysis. DLAT was identified as the only prognostic CRG in PAAD (HR = 2.72; 95% CI, 1.10–6.74). Functional enrichment analyses indicated that the basic function of DLAT is closely related to metabolism, and multiple tumor-promoting and immune response-related pathways were enriched in DLAT-high PAAD samples. The influence of DLAT and related genes on cancer immunity was evaluated by comprehensive immune infiltration analyses, which revealed the value of these genes as biomarkers for evaluating the sensitivity to immunotherapy. Additionally, high DLAT expression induced drug resistance, and significantly increased resistance to commonly used chemotherapeutics in PAAD, such as gemcitabine, oxaliplatin, 5-fluorouracil, and irinotecan. In conclusion, our study preliminarily revealed the prognostic value of DLAT, which is correlated with PAAD progression, chemoresistance, and immune infiltration, providing a valuable reference for PAAD treatment. However, our findings need to be confirmed by further in vivo and in vitro experiments.

Bovine tumor necrosis factor-alpha Increases IL-6, IL-8, and PGE2 in bovine fibroblast-like synoviocytes by metabolic reprogramming

Lameness is a common condition in dairy cattle caused by infectious or noninfectious agents. Joint lesions are the second most common cause of lameness and can be diagnosed in association with the presentation of digit injuries. Fibroblast-like synoviocyte (FLS) are predominant cells of synovia and play a key role in the pathophysiology of joint diseases, thus increasing the expression of proinflammatory mediators. Tumor necrosis factor-alpha (TNF-α) is a potent proinflammatory cytokine involved in cyclooxygenase 2 (COX-2) and proinflammatory cytokine expression in FLS. Previously, TNF-α was demonstrated to increase hypoxia-inducible Factor 1 (HIF-1), a transcription factor that rewires cellular metabolism and increases the expression of interleukin (IL)-6 in bovine FLS (bFLS). Despite this, the proinflammatory effects of TNF-α in bFLS on metabolic reprogramming have been poorly studied. We hypothesized that TNF-α increases glycolysis and in this way controls the expression of IL-6, IL-8, and COX-2 in bFLS. Results first, gas chromatography/mass spectrometry (GC/MS)-based untargeted metabolomics revealed that bTNF-α altered the metabolism of bFLS, increasing glucose, isoleucine, leucine, methionine, valine, tyrosine, and lysine and decreasing malate, fumarate, α-ketoglutarate, stearate, palmitate, laurate, aspartate, and alanine. In addition, metabolic flux analysis using D-glucose-¹³C₆ demonstrated an increase of pyruvate and a reduction in malate and citrate levels, suggesting a decreased flux toward the tricarboxylic acid cycle after bTNF-α stimulation. However, bTNF-α increased lactate dehydrogenase subunit A (LDHA), IL-6, IL-8, IL-1β and COX-2 expression, which was dependent on glycolysis and the PI3K/Akt pathway. The use of FX11 and dichloroacetate (DCA), an inhibitor of LDHA and pyruvate dehydrogenase kinase (PDK) respectively, partially reduced the expression of IL-6. Our results suggest that bTNF-α induces metabolic reprogramming that favors glycolysis in bFLS and increases IL-6, IL-8, IL-1β and COX-2/PGE2.

Increased Expression of the Mitochondrial Glucocorticoid Receptor Enhances Tumor Aggressiveness in a Mouse Xenograft Model

Mitochondria are important organelles for cellular physiology as they generate most of the energy requirements of the cell and orchestrate many biological functions. Dysregulation of mitochondrial function is associated with many pathological conditions, including cancer development. Mitochondrial glucocorticoid receptor (mtGR) is proposed as a crucial regulator of mitochondrial functions via its direct involvement in the regulation of mitochondrial transcription, oxidative phosphorylation (OXPHOS), enzymes biosynthesis, energy production, mitochondrial-dependent apoptosis, and regulation of oxidative stress. Moreover, recent observations revealed the interaction of mtGR with the pyruvate dehydrogenase (PDH), a key player in the metabolic switch observed in cancer, indicating direct involvement of mtGR in cancer development. In this study, by using a xenograft mouse model of mtGR-overexpressing hepatocarcinoma cells, we showed increased mtGR-associated tumor growth, which is accompanied by reduced OXPHOS biosynthesis, reduction in PDH activity, and alterations in the Krebs cycle and glucose metabolism, metabolic alterations similar to those observed in the Warburg effect. Moreover, autophagy activation is observed in mtGR-associated tumors, which further support tumor progression via increased precursors availability. Thus, we propose that increased mitochondrial localization of mtGR is associated with tumor progression possible via mtGR/PDH interaction, which could lead to suppression of PDH activity and modulation of mtGR-induced mitochondrial transcription that ends up in reduced OXPHOS biosynthesis and reduced oxidative phosphorylation versus glycolytic pathway energy production, in favor of cancer cells.

Pyruvate dehydrogenase B regulates myogenic differentiation via the FoxP1-Arih2 axis

BACKGROUND

Sarcopenia, the age-related decline in skeletal muscle mass and function, diminishes life quality in elderly people. Improving the capacity of skeletal muscle differentiation is expected to counteract sarcopenia. However, the mechanisms underlying skeletal muscle differentiation are complex, and effective therapeutic targets are largely unknown.

METHODS

The human Gene Expression Omnibus database, aged mice and primary skeletal muscle cells were used to assess the expression level of pyruvate dehydrogenase B (PDHB) in human and mouse aged state. d-Galactose (d-gal)-induced sarcopenia mouse model and two classic cell models (C2C12 and HSkMC) were used to assess the myogenic effect of PDHB and the underlying mechanisms via immunocytochemistry, western blotting, quantitative real-time polymerase chain reaction, RNA interference or overexpression, dual-luciferase reporter assay, RNA sequencing and untargeted metabolomics.

RESULTS

We identified that a novel target PDHB promoted myogenic differentiation. PDHB expression decreased in aged mouse muscle relative to the young state (-50% of mRNA level, P < 0.01) and increased during mouse and primary human muscle cell differentiation (+3.97-fold, P < 0.001 and +3.79-fold, P < 0.001). Knockdown or overexpression of PDHB modulated the expression of genes related to muscle differentiation, namely, myogenic factor 5 (Myf5) (-46%, P < 0.01 and -27%, P < 0.05; +1.8-fold, P < 0.01), myogenic differentiation (MyoD) (-55%, P < 0.001 and -34%, P < 0.01; +2.27-fold, P < 0.001), myogenin (MyoG) (-60%, P < 0.001 and -70%, P < 0.001; +5.46-fold, P < 0.001) and myosin heavy chain (MyHC) (-70%, P < 0.001 and -69%, P < 0.001; +3.44-fold, P < 0.001) in both C2C12 cells and HSkMC. Metabolomic and transcriptomic analyses revealed that PDHB knockdown suppressed pyruvate metabolism (P < 0.001) and up-regulated ariadne RBR E3 ubiquitin protein ligase 2 (Arih2) (+7.23-fold, P < 0.001) in cellular catabolic pathways. The role of forkhead box P1 (FoxP1) (+4.18-fold, P < 0.001)-mediated Arih2 transcription was the key downstream regulator of PDHB in muscle differentiation. PDHB overexpression improved d-gal-induced muscle atrophy in mice, which was characterized by significant increases in grip strength, muscle mass and mean muscle cross-sectional area (1.19-fold to 1.5-fold, P < 0.01, P < 0.05 and P < 0.001).

CONCLUSIONS

The comprehensive results show that PDHB plays a sarcoprotective role by suppressing the FoxP1-Arih2 axis and may serve as a therapeutic target in sarcopenia.

Roles of cuproptosis-related gene DLAT in various cancers: a bioinformatic analysis and preliminary verification on pro-survival autophagy

Background

Studies have shown that the expressions and working mechanisms of Dihydrolipoamide S-acetyltransferase (DLAT) in different cancers vary. It is necessary to analyze the expressions and regulatory roles of DLAT in tumors systematically.

Methods

Online public-platform literature on the relationships between DLAT expression levels and tumor prognosis, methylation status, genetic alteration, drug sensitivity, and immune infiltration has been reviewed. The literature includes such documents as The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA), Tumor Immune Estimation Resource 2.0 (TIMER2.0), Gene Expression Profiling Interactive Analysis 2 (GEPIA2) and Receiver Operating Characteristic plotter (ROC plotter). The molecular mechanisms of DLAT were explored with the Gene Set Enrichment Analysis (GSEA). The relationship between down-regulated DLAT and autophagy in two liver hepatocellular carcinoma (LIHC) cell lines was confirmed with the western blot method, colony formation assay, and transmission electron microscopy. Tissue microarrays were validated through the immunohistochemical staining of DLAT.

Results

DLAT is upregulated in the LIHC, lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC), and stomach adenocarcinoma (STAD) tumors but is down-regulated in the head and neck squamous cell carcinoma (HNSC) and kidney renal clear cell carcinoma (KIRC) tumors in comparison with normal tissues. For LIHC patients treated with 5-Fluorouracil and Lenvatinib, the DLAT levels of those in the drug-resistant group are significantly high. In LIHC cells, autophagy will be inhibited, and cell death will be induced when DLAT breaks down. Moreover, there exist positive correlations between DLAT expression levels and infiltration of B cells, DC cells, Tregs, and CD8+ T cells in kidney chromophobe (KICH), breast invasive carcinoma (BRCA), prostate adenocarcinoma (PRAD), LIHC and HPV+ HNSC. In LIHC, markers of Tregs are positively correlated with DLAT. Compared with those of normal tissues, the staining intensity of DLAT and the amount of Tregs marker CD49d in LIHC increase.

Conclusions

Through this study, the expressions of DLAT in various cancer types can be understood comprehensively. It suggests that DLAT may be a prognostic marker for LIHC, LUAD, LUSC, STAD and KIRC. A high DLAT expression in LIHC may promote tumorigenesis by stimulating autophagy and inhibiting anti-tumor immunity.

SERBP1 affects the apoptotic level by regulating the expression and alternative splicing of cellular and metabolic process genes in HeLa cells

Background

RNA-binding proteins (RBPs) have important roles in orchestrating posttranscriptional regulation and modulating many tumorigenesis events. SERBP1 has been recognized as an important regulator in multiple cancers, while it remains unclear whether SERBP1-regulated gene expression at the transcriptome-wide level is significantly correlated with tumorigenesis.

Methods

We overexpressed SERBP1 in HeLa cells and explored whether SERBP1 overexpression (SERBP1-OE) affects the proliferation and apoptosis of HeLa cells. We analyzed the transcriptome-wide gene expression changes and alternative splicing changes mediated by SERBP1-OE using the transcriptome sequencing method (RNA-seq). RT-qPCR was conducted to assay SERBP1-regulated alternative splicing.

Results

SERBP1-OE induced the apoptosis of HeLa cells. The downregulated genes were strongly enriched in the cell proliferation and apoptosis pathways according to the GO analysis, including FOS, FOSB, PAK6 and RAB26. The genes undergoing at least one SERBP1-regulated alternative splicing event were enriched in transcriptional regulation, suggesting a mechanism of the regulation of gene expression, and in pyruvate and fatty acid metabolic processes critical for tumorigenesis events. The SERBP1-regulated alternative splicing of ME3, LPIN3, CROT, PDP1, SLC27A1 and ALKBH7 was validated by RT-qPCR analysis.

Conclusions

We for the first time demonstrated the cellular function and molecular targets of SERBP1 in HeLa cells at transcriptional and post-transcriptional levels. The SERBP1-regulated gene expression and alternative splicing networks revealed by this study provide important information for exploring the functional roles and regulatory mechanisms of SERBP1 in cancer development and progression.

Long non-coding RNAs affecting cell metabolism in cancer

Metabolic reprogramming is commonly recognized as one important hallmark of cancers. Cancer cells present significant alteration of glucose metabolism, oxidative phosphorylation, and lipid metabolism. Recent findings demonstrated that long non-coding RNAs control cancer development and progression by modulating cell metabolism. Here, we give an overview of breast cancer metabolic reprogramming and the role of long non-coding RNAs in driving cancer-specific metabolic alteration.

A novel organic arsenic derivative MZ2 remodels metabolism and triggers mtROS-mediated apoptosis in acute myeloid leukemia

PURPOSE

Acute myeloid leukemia (AML) is one of the most common neoplasms in adults, and it is difficult to achieve satisfactory results with conventional drugs. Here, we synthesized a novel organic arsenic derivative MZ2 and evaluated its ability to remodel energy metabolism to achieve anti-leukemia.

METHODS

MZ2 was characterized by the average 1-min full mass spectra analysis. Biological methods such as Western blot, qPCR, flow cytometry and confocal microscopy were used to assess the mode and mechanism of MZ2-induced death. The in vivo efficacy of MZ2 was assessed by constructing a patient-derived xenograft (PDX) AML model.

RESULTS

Unlike the precursor organic arsenical Z2, MZ2 can effectively reduce the level of aerobic glycolysis. Our in-depth found that MZ2 inhibited the expression of PDK2 in a dose-dependent manner and did not affect the expression of LDHA, another key enzyme of the glycolytic pathway. MZ2 reconstituted energy metabolism to induce the generation of mitochondrial ROS (mtROS) and then triggerd intrinsic apoptosis pathway. We also assessed whether MZ2 generates autophagy and results showed that MZ2 can induce autophagy of AML cells, which may be associated with the precursor organic arsenic drug. In vivo, MZ2 effectively attenuated leukemia progression in mice, and immunohistochemical results suggested its PDK2 inhibitory effect.

CONCLUSION

In summary, the novel organic arsine derivative MZ2 exhibited excellent anti-tumor effects in acute myeloid leukemia, which may provide a potential strategy for the treatment of acute myeloid leukemia.

Cryptotanshinone suppresses tumorigenesis by inhibiting lipogenesis and promoting reactive oxygen species production in KRAS‑activated pancreatic cancer cells

Pyruvate dehydrogenase kinase 4 (PDK4) is an important regulator of energy metabolism. Previously, knockdown of PDK4 by specific small interfering RNAs (siRNAs) have been shown to suppress the expression of Kirsten rat sarcoma viral oncogene homolog (KRAS) and the growth of lung and colorectal cancer cells, indicating that PDK4 is an attractive target of cancer therapy by altering energy metabolism. The authors previously reported that a novel small molecule, cryptotanshinone (CPT), which inhibits PDK4 activity, suppresses the in vitro three-dimensional (3D)-spheroid formation and in vivo tumorigenesis of KRAS-activated human pancreatic and colorectal cancer cells. The present study investigated the molecular mechanism of CPT-induced tumor suppression via alteration of glutamine and lipid metabolism in human pancreatic and colon cancer cell lines with mutant and wild-type KRAS. The antitumor effect of CPT was more pronounced in the cancer cells containing mutant KRAS compared with those containing wild-type KRAS. CPT treatment decreased glutamine and lipid metabolism, affected redox regulation and increased reactive oxygen species (ROS) production in the pancreatic cancer cell line MIAPaCa-2 containing mutant KRAS. Suppression of activated KRAS by specific siRNAs decreased 3D-spheroid formation, the expression of acetyl-CoA carboxylase 1 and fatty acid synthase (FASN) and lipid synthesis. The suppression also reduced glutathione-SH/glutathione disulfide and increased the production of ROS. Knockdown of FASN suppressed lipid synthesis in MIAPaCa-2 cells, partially promoted ROS production and mildly suppressed 3D-spheroid formation. These results indicated that CPT reduced tumorigenesis by inhibiting lipid metabolism and promoting ROS production in a mutant KRAS-dependent manner. This PDK4 inhibitor could serve as a novel therapeutic drug for KRAS-driven intractable cancers via alteration of cell metabolism.

Relationship between metabolic reprogramming and drug resistance in breast cancer

Breast cancer is the leading cause of cancer death in women. At present, chemotherapy is the main method to treat breast cancer in addition to surgery and radiotherapy, but the process of chemotherapy is often accompanied by the development of drug resistance, which leads to a reduction in drug efficacy. Furthermore, mounting evidence indicates that drug resistance is caused by dysregulated cellular metabolism, and metabolic reprogramming, including enhanced glucose metabolism, fatty acid synthesis and glutamine metabolic rates, is one of the hallmarks of cancer. Changes in metabolism have been considered one of the most important causes of resistance to treatment, and knowledge of the mechanisms involved will help in identifying potential treatment deficiencies. To improve women’s survival outcomes, it is vital to elucidate the relationship between metabolic reprogramming and drug resistance in breast cancer. This review analyzes and investigates the reprogramming of metabolism and resistance to breast cancer therapy, and the results offer promise for novel targeted and cell-based therapies.

A Cuproptosis-Related Gene Model For Predicting the Prognosis of Clear Cell Renal Cell Carcinoma

Despite advances in its treatment, patients diagnosed with clear cell renal cell carcinoma (ccRCC) have a poor prognosis. The mechanism of cuproptosis has been found to differ from other mechanisms that regulate cell death, including apoptosis, iron poisoning, pyrophosphate poisoning, and necrosis. Cuproptosis is an essential component in the regulation of a wide variety of biological processes, such as cell wall remodeling and oxidative stress responses. However, cuproptosis-related genes’ expression in ccRCC patients and their association with the patient’s prognosis remain ambiguous. Evaluation of The Cancer Genome Atlas (TCGA) identified 11 genes associated with cuproptosis that were differently expressed in ccRCC and nearby nontumor tissue. To construct a multigene prognostic model, the prognostic value of 11 genes was assessed and quantified. A signature was constructed by least absolute shrinkage and selection operator (LASSO) Cox regression analysis, and this signature was used to separate ccRCC patients into different risk clusters, with low-risk patients having a much better prognosis. This five-gene signature, when combined with patients’ clinical characteristics, might serve as one independent predictor of overall survival (OS) in ccRCC patients. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis demonstrated that cuproptosis-related genes were enriched in patients with ccRCC. Then, quantitative real-time PCR (qPCR) was employed to verify these genes’ expression. Generally, research has indicated that cuproptosis-related genes are important in tumor immunity and can predict OS of ccRCC patients.

Alpha-Lipoic Acid Protects Against Doxorubicin-Induced Cardiotoxicity by Regulating Pyruvate Dehydrogenase Kinase 4

As a widely used anti-tumor anthracycline, the accumulation of Doxorubicin (DOX) in body causes irreparable cardiomyocyte damage and therefore is limited in clinical application. Strategies to prevent from DOX-associated cardiotoxicity are urgent for patients who undergo DOX-based chemotherapy. Since oxidative stress injury being the major reason for myocardial toxicity of DOX, here we demonstrated that, Alpha-lipoic acid (ALA), which is a reductive agent, plays a cardioprotective role in attenuating DOX-induced cardiotoxicity by inhibiting pyruvate dehydrogenase kinase 4 (PDK4) expression. In vivo, the beneficial effect of ALA was evidenced by increased survival rate, mechanical contraction, and oxidative phosphorylation, while decreased reactive oxidative species (ROS) and apoptosis. In vitro, PDK4 overexpression remarkably increased DOX-induced apoptosis and ROS production in H9C2 cells. Notably, the protective effect of ALA was abrogated by PDK4 overexpression. We further used PDK4 knockout mice to identify the role of PDK4 in DOX-induced cardiotoxicity. Results elicited that PDK4 deficiency showed a consistent effect in protecting DOX cardiotoxicity as ALA treatment, which was evidenced by restored redox homeostasis and mitochondrial metabolism, finally inhibited myocardial injury. In conclusion, the cardioprotective role of ALA against DOX cardiotoxicity was dependent on PDK4-mediated regulation of oxidative stress and mitochondria metabolism.

Refining the Role of Pyruvate Dehydrogenase Kinases in Glioblastoma Development

Glioblastoma (GB) are the most frequent brain cancers. Aggressive growth and limited treatment options induce a median survival of 12–15 months. In addition to highly proliferative and invasive properties, GB cells show cancer-associated metabolic characteristics such as increased aerobic glycolysis. Pyruvate dehydrogenase (PDH) is a key enzyme complex at the crossroads between lactic fermentation and oxidative pathways, finely regulated by PDH kinases (PDHKs). PDHKs are often overexpressed in cancer cells to facilitate high glycolytic flux. We hypothesized that targeting PDHKs, by disturbing cancer metabolic homeostasis, would alter GB progression and render cells vulnerable to additional cancer treatment. Using patient databases, distinct expression patterns of PDHK1 and PDHK2 in GB tissues were obvious. To disturb protumoral glycolysis, we modulated PDH activity through the genetic or pharmacological inhibition of PDHK in patient-derived stem-like spheroids. Striking effects of PDHKs inhibition using dichloroacetate were observed in vitro on cell morphology and metabolism, resulting in increased intracellular ROS levels and decreased proliferation and invasion. In vivo findings confirmed a reduction in tumor size and better survival of mice implanted with PDHK1 and PDHK2 knockout cells. Adding a radiotherapeutic protocol further resulted in a reduction in tumor size and improved mouse survival in our model.

Essential role of aerobic glycolysis in epithelial-to-mesenchymal transition during carcinogenesis

Epithelial-to-mesenchymal transition (EMT) confers the most lethal characteristics to cancer cells i.e., metastasis and resistance to chemo-and-radio-therapy, and therefore exhibit an appealing target in the field of oncology. Research in the past decade has demonstrated the crucial role of aerobic glycolysis in EMT, which is generally credited as the glucose metabolism for the creation of biomass such as fatty acids, amino acids, and nucleotides thereby providing building blocks for limitless proliferation. In the present review, apart from discussing EMT's evident role in the metastatic process and cancer stemness, we also talked about the vital role of glycolytic enzymes viz. GLUTs, HKs, PGI, PFK-1, aldolase, enolase, PK, LDHA, etc. in the induction of the EMT process in cancerous cells.

Pyruvate Dehydrogenase A1 Phosphorylated by Insulin Associates with Pyruvate Kinase M2 and Induces LINC00273 through Histone Acetylation

Insulin potently promotes cell proliferation and anabolic metabolism along with a reduction in blood glucose levels. Pyruvate dehydrogenase (PDH) plays a pivotal role in glucose metabolism. Insulin increase PDH activity by attenuating phosphorylated Ser293 PDH E1α (p-PDHA1) in normal liver tissue. In contrast to normal hepatocytes, insulin enhanced p-PDHA1 level and induced proliferation of hepatocellular carcinoma HepG2 cells. Here, we attempted to find a novel function of p-PDHA1 in tumorigenesis upon insulin stimulation. We found that p-Ser293 E1α, but not the E2 or E3 subunit of pyruvate dehydrogenase complex (PDC), co-immunoprecipitated with pyruvate kinase M2 (PKM2) upon insulin. Of note, the p-PDHA1 along with PKM2 translocated to the nucleus. The p-PDHA1/PKM2 complex was associated with the promoter of long intergenic non-protein coding (LINC) 00273 gene (LINC00273) and recruited p300 histone acetyl transferase (HAT) and ATP citrate lyase (ACL), leading to histone acetylation. Consequently, the level of transcription factor ZEB1, an epithelial–mesenchymal transition (EMT) marker, was promoted through increased levels of LINC00273, resulting in cell migration upon insulin. p-PDHA1, along with PKM2, may be crucial for transcriptional regulation of specific genes through epigenetic regulation upon insulin in hepatocarcinoma cells.

Pyruvate Dehydrogenase Kinase Inhibition by Dichloroacetate in Melanoma Cells Unveils Metabolic Vulnerabilities

Melanoma is characterized by high glucose uptake, partially mediated through elevated pyruvate dehydrogenase kinase (PDK), making PDK a potential treatment target in melanoma. We aimed to reduce glucose uptake in melanoma cell lines through PDK inhibitors dichloroacetate (DCA) and AZD7545 and through PDK knockdown, to inhibit cell growth and potentially unveil metabolic co-vulnerabilities resulting from PDK inhibition. MeWo cells were most sensitive to DCA, while SK-MEL-2 was the least sensitive, with IC₅₀ values ranging from 13.3 to 27.0 mM. DCA strongly reduced PDH phosphorylation and increased the oxygen consumption rate:extracellular acidification rate (OCR:ECAR) ratio up to 6-fold. Knockdown of single PDK isoforms had similar effects on PDH phosphorylation and OCR:ECAR ratio as DCA but did not influence sensitivity to DCA. Growth inhibition by DCA was synergistic with the glutaminase inhibitor CB-839 (2- to 5-fold sensitization) and with diclofenac, known to inhibit monocarboxylate transporters (MCTs) (3- to 8-fold sensitization). CB-839 did not affect the OCR:ECAR response to DCA, whereas diclofenac strongly inhibited ECAR and further increased the OCR:ECAR ratio. We conclude that in melanoma cell lines, DCA reduces proliferation through reprogramming of cellular metabolism and synergizes with other metabolically targeted drugs.

The Critical Role Played by Mitochondrial MITF Serine 73 Phosphorylation in Immunologically Activated Mast Cells

In recent years, growing evidence has indicated the pivotal role of mitochondria in mast cell immunological activation. We have previously reported a decrease in degranulation and cytokine secretion following the inhibition of pyruvate dehydrogenase (PDH) either by CPI-613 (PDH inhibitor/anti-cancer drug) or through its interaction with mitochondrial microphthalmia-associated transcription factor (MITF). In the present study, we further explored the role played by mitochondrial MITF in mast cell exocytosis using rat basophil leukemia cells [RBL], as well as mouse bone marrow-derived mast cells (BMMCs). Here, we report that mast cell degranulation, cytokine secretion and oxidative phosphorylation (OXPHOS) activities were associated with phosphorylation of Serine 73 of mitochondrial MITF, controlled by extracellular signals regulated by protein kinase (ERK1/2) activity. Also, we report here that decreased OXPHOS activity following ERK1/2 inhibition (U0126 treatment) during IgE-Ag activation was mediated by the dephosphorylation of Serine 73 mitochondrial MITF, which inhibited its association with PDH. This led to a reduction in mast cell reactivity. In addition, a phosphorylation-mimicking mitochondrial MITF-S73D positively regulated the mitochondrial activity, thereby supporting mast cell degranulation. Thus, the present research findings highlight the prominence of mitochondrial MITF Serine 73 phosphorylation in immunologically activated mast cells.

Metabolic Reprogramming in Response to Alterations of Mitochondrial DNA and Mitochondrial Dysfunction in Gastric Adenocarcinoma

We used gastric cancer cell line AGS and clinical samples to investigate the roles of mitochondrial DNA (mtDNA) alterations and mitochondrial respiratory dysfunction in gastric adenocarcinoma (GAC). A total of 131 clinical samples, including 17 normal gastric mucosa (N-GM) from overweight patients who had received sleeve gastrectomy and 57 paired non-cancerous gastric mucosae (NC-GM) and GAC from GAC patients who had undergone partial/subtotal/total gastrectomy, were recruited to examine the copy number and D310 sequences of mtDNA. The gastric cancer cell line AGS was used with knockdown (KD) mitochondrial transcription factor A (TFAM) to achieve mitochondrial dysfunction through a decrease of mtDNA copy number. Parental (PT), null-target (NT), and TFAM-KD-(A/B/C) represented the parental, control, and TFAM knocked-down AGS cells, respectively. These cells were used to compare the parameters reflecting mitochondrial biogenesis, glycolysis, and cell migration activity. The median mtDNA copy numbers of 17 N-GM, 57 NC-GM, and 57 GAC were 0.058, 0.055, and 0.045, respectively. The trend of decrease was significant (p = 0.030). In addition, GAC had a lower mean mtDNA copy number of 0.055 as compared with the paired NC-GM of 0.078 (p < 0.001). The mean mtDNA copy number ratio (mtDNA copy number of GAC/mtDNA copy number of paired NC-GM) was 0.891. A total of 35 (61.4%) GAC samples had an mtDNA copy number ratio ≤0.804 (p = 0.017) and 27 (47.4%) harbored a D310 mutation (p = 0.047), and these patients had shorter survival time and poorer prognosis. After effective knockdown of TFAM, TFAM-KD-B/C cells expressed higher levels of hexokinase II (HK-II) and v-akt murine thymoma viral oncogene homolog 1 gene (AKT)-encoded AKT, but lower levels of phosphorylated pyruvate dehydrogenase (p-PDH) than did the NT/PT AGS cells. Except for a higher level of p-PDH, the expression levels of these proteins remained unchanged in TFAM-KD-A, which had a mild knockdown of TFAM. Compared to those of NT, TFAM-KD-C had not only a lower mtDNA copy number (p = 0.050), but also lower oxygen consumption rates (OCR), including basal respiration (OCR_BR), ATP-coupled respiration (OCR_ATP), reserve capacity (OCR_RC), and proton leak (OCR_PL)(all with p = 0.050). In contrast, TFAM-KD-C expressed a higher extracellular acidification rate (ECAR)/OCR_BR ratio (p = 0.050) and a faster wound healing migration at 6, 12, and 18 h, respectively (all with p = 0.050). Beyond a threshold, the decrease in mtDNA copy number, the mtDNA D310 mutation, and mitochondrial dysfunction were involved in the carcinogenesis and progression of GACs. Activation of PDH might be considered as compensation for the mitochondrial dysfunction in response to glucose metabolic reprogramming or to adjust mitochondrial plasticity in GAC.

Pyruvate dehydrogenase inactivation causes glycolytic phenotype in BAP1 mutant uveal melanoma

Effective therapeutic options are still lacking for uveal melanoma (UM) patients who develop metastasis. Metastatic traits of UM are linked to BRCA1-associated protein 1 (BAP1) mutations. Cell metabolism is re-programmed in UM with BAP1 mutant UM, but the underlying mechanisms and opportunities for therapeutic intervention remain unclear. BAP1 mutant UM tumors have an elevated glycolytic gene expression signature, with increased expression of pyruvate dehydrogenase (PDH) complex and PDH kinase (PDHK1). Furthermore, BAP1 mutant UM cells showed higher levels of phosphorylated PDHK1 and PDH that was associated with an upregulated glycolytic profile compared to BAP1 wild-type UM cells. Suppressing PDHK1-PDH phosphorylation decreased glycolytic capacity and cell growth, and induced cell cycle arrest of BAP1 mutant UM cells. Our results suggest that PDHK1-PDH phosphorylation is a causative factor of glycolytic phenotypes found in BAP1 mutant UM and propose a therapeutic opportunity for BAP1 mutant UM patients.

Targeting glucose metabolism to develop anticancer treatments and therapeutic patents

INTRODUCTION

One of the most distinctive hallmarks of cancer cells is increased glucose consumption for aerobic glycolysis which is named the Warburg effect. In recent decades, extensive research has been carried out to exploit this famous phenomenon, trying to detect promising targetable vulnerabilities in altered metabolism to fight cancer. Targeting aberrant glucose metabolism can perturb cancer malignant proliferation and even induce programmed cell death.

AREAS COVERED

This review covered the recent patents which focused on targeting key glycolytic enzymes including hexokinase, pyruvate dehydrogenase kinases and lactate dehydrogenase for cancer treatment.

EXPERT OPINION

Compared with the conventional cancer treatment, specifically targeting the well-known Achilles heel Warburg effect has attracted considerable attention. Although there is still no single glycolytic agent for clinical cancer treatment, the combination of glycolytic inhibitor with conventional anticancer drug or the combined use of multiple glycolytic inhibitors are being investigated extensively in recent years, which could emerge as attractive anticancer strategies.

Mitochondrial Dysfunction as a Hallmark of Environmental Injury

Environmental factors including diet, sedentary lifestyle and exposure to pollutants largely influence human health throughout life. Cellular and molecular events triggered by an exposure to environmental pollutants are extremely variable and depend on the age, the chronicity and the doses of exposure. Only a fraction of all relevant mechanisms involved in the onset and progression of pathologies in response to toxicants has probably been identified. Mitochondria are central hubs of metabolic and cell signaling responsible for a large variety of biochemical processes, including oxidative stress, metabolite production, energy transduction, hormone synthesis, and apoptosis. Growing evidence highlights mitochondrial dysfunction as a major hallmark of environmental insults. Here, we present mitochondria as crucial organelles for healthy metabolic homeostasis and whose dysfunction induces critical adverse effects. Then, we review the multiple mechanisms of action of pollutants causing mitochondrial toxicity in link with chronic diseases. We propose the Aryl hydrocarbon Receptor (AhR) as a model of “exposome receptor”, whose activation by environmental pollutants leads to various toxic events through mitochondrial dysfunction. Finally, we provide some remarks related to mitotoxicity and risk assessment.

Dihydrolipoamide dehydrogenase, pyruvate oxidation, and acetylation-dependent mechanisms intersecting drug iatrogenesis

In human metabolism, pyruvate dehydrogenase complex (PDC) is one of the most intricate and large multimeric protein systems representing a central hub for cellular homeostasis. The worldwide used antiepileptic drug valproic acid (VPA) may potentially induce teratogenicity or a mild to severe hepatic toxicity, where the underlying mechanisms are not completely understood. This work aims to clarify the mechanisms that intersect VPA-related iatrogenic effects to PDC-associated dihydrolipoamide dehydrogenase (DLD; E3) activity. DLD is also a key enzyme of α-ketoglutarate dehydrogenase, branched-chain α-keto acid dehydrogenase, α-ketoadipate dehydrogenase, and the glycine decarboxylase complexes. The molecular effects of VPA will be reviewed underlining the data that sustain a potential interaction with DLD. The drug-associated effects on lipoic acid-related complexes activity may induce alterations on the flux of metabolites through tricarboxylic acid cycle, branched-chain amino acid oxidation, glycine metabolism and other cellular acetyl-CoA-connected reactions. The biotransformation of VPA involves its complete β-oxidation in mitochondria causing an imbalance on energy homeostasis. The drug consequences as histone deacetylase inhibitor and thus gene expression modulator have also been recognized. The mitochondrial localization of PDC is unequivocal, but its presence and function in the nucleus were also demonstrated, generating acetyl-CoA, crucial for histone acetylation. Bridging metabolism and epigenetics, this review gathers the evidence of VPA-induced interference with DLD or PDC functions, mainly in animal and cellular models, and highlights the uncharted in human. The consequences of this interaction may have significant impact either in mitochondrial or in nuclear acetyl-CoA-dependent processes.

Hepatic Glucose Metabolism and Its Disorders in Fish

Carbohydrate, which is the most abundant nutrient in plant-sourced feedstuffs, is an economically indispensable component in commercial compound feeds for fish. This nutrient can enhance the physical quality of diets and allow for pellet expansion during extrusion. There is compelling evidence that an excess dietary intake of starch causes hepatic disorders, thereby further reducing the overall food consumption and growth performance of fish species. Among the severe metabolic disturbances are glycogenic hepatopathy (hepatomegaly caused by the excessive accumulation of glycogen in hepatocytes) and hepatic steatosis (the accumulation of large vacuoles of triacylglycerols in hepatocytes). The development of those disorders is mainly due to the limited ability of fish to oxidize glucose and control blood glucose concentration. The prolonged elevations of blood glucose increase glucose intake by the liver, and excess glucose is stored either as glycogen through glycogenesis in hepatocytes or as triglycerides via lipogenesis in tissues, depending on the species. In some fish species (e.g., largemouth bass), the liver has a low ability to regulate glycolysis, gluconeogenesis, and glycogen breakdown in response to high starch intake. For most species of fish, the liver size increases with lipid or glycogen accumulation when they have a high starch intake. It is a challenge to develop the same set of diagnostic criteria for all fish species as their physiology or metabolic patterns differ. Although glycogenic hepatopathy appears to be a common disease in carnivorous fish, it has been under-recognized in many studies. As a result, understanding these diseases and their pathogeneses in different fish species is crucial for manufacturing cost-effective pellet diets to promote the health, growth, survival, and feed efficiency of fish in future.